A semiconductor device for detecting a flow rate of fluid is known as disclosed in, for example, Japanese Patent No. 3,468,731 corresponding to U.S. Pat. No. 6,490,915.
In a semiconductor of this kind, a heating element (heating resistance element) and a temperature sensing element (temperature sensing resistance element) for sensing temperature of a portion around the heating element are formed on a semiconductor substrate, and a flow detector for detecting flow rate of a fluid is constructed.
Fluid (for example, air) contains moisture. When the flow rate of the fluid is detected by the semiconductor device, therefore, an error occurs only by the amount of the moisture content. Such an error is not preferred in uses requiring high-precision flow rate (air volume), particularly, like in fuel injection control of an internal combustion engine of a vehicle.